A molecular genetic approach using transgenic arthropods as bioreporter/biomarker of environmental heavy metal pollution will be developed. In this model system, mosquitoes will be stably transformed with our metal-responsive construct, pMT-1, which contains the Drosophila metallothionein (MT) promoter regulating expression of the beta- galactosidase gene. The construct is inducible in transformed mosquito cells exposed to copper and probably most other heavy metals. Individually induced cells can be detected colorometrically. In these studies, the construct will be used to stably transform mosquitoes, which will then be exposed to specific heavy metals (alone or in combination) and to defined chemical mixtures likely to be encountered in hazardous waste sites. Environmentally relevant concentrations and exposure regimens will be followed. The studies will reveal the potential for use of transgenic arthropods as sensitive and specific bioreporters for environmental contamination. In addition, the studies will provide important information concerning the specific cells and organ systems targeted by the hazardous chemicals and the potential toxicological and pathophysiological consequences to the reporter organisms. These laboratory studies will also provide important information concerning the potential molecular genetic response of natural populations of arthropods to heavy metal and chemical mixtures exposure. Such information can potentially be used to develop molecular probes for ascertaining the presence of environmental contaminants in defined ecoystems, to select potential bioreporter systems in a more systematic fashion, and to develop a new generation of sensitive bioreporter systems.